Measuring the load current supplied by a step down or step up switching regulator is a difficult problem. It can be accomplished by placing a resistor in series with the load, and measuring the voltage across this resistor. This approach has a significant disadvantage because it reduces the efficiency of the regulator, and requires an additional pin on the device if the resistor is external.
Another approach is to determine the load current by following the feedback voltage in the control loop. This approach is completely independent of external components and voltage levels, but typically it results in a low gain signal on the order of 1 mV/mA of the load current.
Hence, there is a need for circuitry and methodology substantially independent of external components that would provide an adequate gain to reliably discern between small changes in load current.